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Infection and Immunity, January 2000, p. 264-269, Vol. 68, No. 1
Department of Clinical Biochemistry and
Cellular Science1 and Molecular
Parasitology Laboratory,2 Institute of Molecular
Medicine, The John Radcliffe Hospital, Oxford OX3 9DU, and
Department of Physiology, The Medical School, University of
Birmingham, Birmingham B15 2TT,3 United Kingdom
Received 22 June 1999/Returned for modification 6 August
1999/Accepted 18 October 1999
Adhesion of Plasmodium falciparum-infected erythrocytes
to the endothelial ligand intercellular adhesion molecule 1 (ICAM-1) has been implicated in the pathogenesis of cerebral malaria. Recently, a high-frequency coding polymorphism in the N-terminal domain of ICAM-1
(ICAM-1Kilifi) that is associated with susceptibility to
cerebral disease in Kenya has been described. Preliminary static
adhesion assays suggested that two different selected P. falciparum lines, ITO4-A4 (A4) and ItG-ICAM (ItG), have different
properties of binding to the natural variant proteins ICAM-1 and
ICAM-1Kilifi. Using a flow adhesion assay system, we
have confirmed differences between the two lines in binding of
parasitized erythrocytes to the variant ICAM-1 proteins. Total adhesion
of ItG-infected erythrocytes to ICAM-1 and ICAM-1Kilifi is
greater than that of A4-infected erythrocytes, and erythrocytes infected by both parasite strains show reduced binding to
ICAM-1Kilifi. However, under these physiologically relevant
flow conditions, we have shown differences between A4 and ItG strains
in dynamic rolling behavior on ICAM-1Kilifi. The percentage
of erythrocytes infected with A4 that roll on both ICAM-1 and
ICAM-1Kilifi is greater than that of those infected with
ItG. Also, the rolling velocity of A4-infected erythrocytes on
ICAM-1Kilifi is markedly increased compared to that on
ICAM-1, in contrast to the rolling velocity of ItG-infected
erythrocytes, which is similar on both proteins. These findings suggest
that different parasite lines can vary in their avidity for the same
host ligand, which may have important consequences for the
pathophysiology of P. falciparum malaria.
0019-9567/0/$04.00+0
Differential Binding of Clonal Variants of Plasmodium
falciparum to Allelic Forms of Intracellular Adhesion Molecule
1 Determined by Flow Adhesion Assay
*
Corresponding author. Mailing address: Department of
Clinical Biochemistry and Cellular Science, Level 5 Laboratory, R5501, The John Radcliffe Hospital, Oxford OX3 9DU, United Kingdom. Phone: 44 1865 220536. Fax: 44 1865 222912. E-mail:
sadams{at}enterprise.molbiol.ox.ac.uk
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